Photographic developing system and method

ABSTRACT

AN IMPROVED DEVELOPING SYSTEM FOR DRY OR ESSENTIALLY DRY PHOTOGRAPHIC PROCESSING COMPRISES A PELLICLE CONTAINING PHOTOGRAPHIC DEVELOPER AND A WEB CONTAINING ACTIVATOR FOR THE DEVELOPER. THE SYSTEM MAY ALSO INCLUDE NECLEATING MATERIALS AND COMPLEXING AGENTS FOR POSITIVE PRINT PRODUCTION. THE SYSTEM IS PARTICULARLY SUITABLE FOR SILVER HALIDE MICROFILM PROCESSING AND THE LIKE. IN ONE EMBODIMENT THE PELLICLE IS LAMINATED WITH THE WEB AND THE COMBINATION LAMINATED TO A PHOTOGRAPHIC EMULSION BEARING A LATENT IMAGE TO TRANSFER ACTIVATOR AND DEVELOPER TO THE EMULSION. FOLLOWING DEVELOPMENT AND DELAMINATION, THE PELLICLE REMAINS WITH THE WEB. IN ANOTHER EMBODIMENT, THE PELLICLE IS TEMPORARILY LAMINATED WITH THE WEB TO IMBIDE DEVELOPER INTO THE WEB WHEREUPON THE PELLICLE IS REMOVED AND THE WEB LAMINATED WITH THE PHOTOGRAPHIC EMULSION, AS ABOVE. NUCLEATING AND COMPLEXING AGENTS CAN BE INCLUDED, TO REMAIN WITH THE WEB, TO PROVIDE A POSITIVE PRINT BY DIFFUSION TRANSFER OR TO AID IN STABILIZATION OF THE PHOTOGRAPHIC EMULSION.

July 3o, 1974 J. H. JACOBS ET AL PHOTOGRAPHIC DEVELOPING SYSTEM AND METHoD Filed Sept. 18, 1972 Kl b/ LLI/Ill I I/I I I/I/I I/ *U.s. cl. 96-50 n 'UnitedStates Patent O 3,826,653 PHOTOGRAPHIC DEVELOPING SYSTEM AND METHOD John H. Jacobs, Altadena, and Richard A. Corrigan, Temple City, Calif., and Joseph Gaynor, Cleveland, Ohio, assignors to Bell & Howell Company, Chicago,

' Filed sept. 1s, 1972, ser. No. 290,204

im. ci. cose /26, 5/24, 1/48 1 13 Claims ABSTRACT OF THE DISCLOSURE An improved developing system for dry or essentially dry photographic processing comprises a pellicle containing photographic developer and a web containing activator for thedeveloper. The system may also include nucleating materials and complexing agents for positive print production. The system is particularly suitable for silver halide microfilm processing and the like. In one embodiment the pellicle is laminated with the web and the combination laminated to a photographic emulsion bearing a latent image to transfer activator and developer to the emulsion. Following development and delamination, the pellicle remains with the web. In another embodiment, the pellicle is temporarily laminated with the Iweb to imbide developer into the web whereupon the pellicle is removed and the web laminated with the photographic emulsion, as above. Nucleating and complexing agents can be included, to remain with the web, to provide a positive print by diffusion transfer or to aid in stabilization of the photographic emulsion.

FIELD OF` THE INVENTION The present invention generally relates to photographic processing and more particularly to essentially dry photographic developing.

BACKGROUND AND SUMMARY OF THE INVENTION Various methods have been employed for processing `of silver halide photographic media and the like without the use of free liquids. One well known essentially dry process employs a pod of concentrated reagent which is spread between two sheets in a diffusion transfer system. Other systems employ paper, porous plastic or a hydrophilic colloid such as gelatin lm to carry the processing reagents. The carrier is laminated to the exposed film `which becomes processed by what is termed a monobath solution borne by the carrier. lHowever, such monobath systems lack long term stability because they contain de- -velopers and also activators for the developers. In the presence of activators, the developers are subject to oxidation and destruction. However well packaged the materials may be, oxygen from the atmosphere diffuses into the package and limits the shelf life of the system.

In certain processing systems the foregoing difficulties are overcome by disposing the developers in the silver halide photographic emulsion. However, emulsion-incorporated developers are found to cause fogging and loss of photosensitivity, particularly when the medium is stored for an appreciable time before use. Similar difficulties, albeit of lesser extent, are encountered when the developer is embodied in a separate layer carried on a surface of the emulsion.

Accordingly, there is a need to provide a simple, effective system and method for dry processing photographic media such as silver halide microlm land the like without causing fogging or loss of sensitivity of the film. Such system should have a long shelf life without'substantial deterioration.

3,826,653 Patented July 30, 1974 ICC -'Ihe present invention satisfies the foregoing needs by providing complete separation of the developer, activator and photographic emulsion until processing is required. At that point, these components are simultaneously or sequentially joined together in a manner to activate the developer and place it in contact with the medium. In particular, the developer is incorporated in a separate sheet or pellicle obtained by coating the developer in a binder, such as polyvinyl alcohol, onto a support. In one embodiment, the pellicle is stripped from the support, which is suitably subbed, and laminated with a web containing an activator. The combination is then laminated to the photographic emulsion bearing a latent image to transfer activator and developer to the emulsion. Following development and delamination, the pellicle remains with the web.

In another embodiment the pellicle, which may be stripped from the support or permanently adhered thereto, is temporarily laminated with the web to imbide developer into the web whereupon the pellicle is removed and the web laminated with the photographic emulsion, as above.

In either embodiment, a diffusion transfer mode of development can be employed by adding nucleating materials either to the developer sheet or in an adjacent layer which remains with the web, and by including a silver halide complexing agent in the web. In this manner, a positive print is produced and virtually all of the unused silver halide may be removed from the photosensitive emulsion in a one-step process resulting in `greater con- Venience and better stabilization of the film.

Further features are set forth in the following detailed description and accompanying drawings of which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic fragmentary sectional view of a first embodiment of the improved developing system of the invention immediately before application to a photographic emulsion;

FIG. 2A is a schematic fragmentary sectional view of a second embodiment of the improved developing system of the invention before transfer of a developer-containing pellicle to an activator-containing web;

FIG. 2B illustrates the system shown in FIG. 2A but after the pellicle transfer; and

FIG. 3 is a schematic fragmentary sectional view of a third embodiment of the improved developing system of the invention before and after transfer of developer from a supported pellicle to a web containing activator.

DEAILED DESCRIPTION As shown schematically in fragmentary section in FIG. l, the first embodiment of the system of the present invention comprises a pellicle 10 containing developer for a photographic latent image and a separate web 12 containing an activator for the developer.

The pellicle 10 may comprise.` any suitable material capable of carrying and releasing the developer as required. The pellicle 10 readily adheres to the surface of web 12 whenAin contact therewith. In this regard, it has been found that it is particularly desirable to employ a thin flexible film of a suitable porous plastic such as polyvinyl alcohol or the like as the carrier (pellicle 10) for the developer. Other suitable film-forming materials which can be used for this purpose include gelatin, agar, polyhydric alcohol (e.g., polyethylene glycol and the like), methylcellulose, sodium alginate and others.

Depending on the particular material selected for the pellicle 10, it may be necessary to provide it'with a suitable backing or support. In the embodiment shown in FIG. 1, however, the pellicle 10 comprises a `sheet lof self-supporting film` which is disposed in a roll on areel or the like (not shown) and is fed intoan area between web 12 and a photographic medium 14 in the form of a silver halide film.

' The' developer utilized in the pellicle 10 can be any suitable material capable of developing a latent photographic image. Usually, the photographic medium is of the silver halide type and, accordingly, the developer can be material such as catechol, hydroquinone, toluhydroquinone, o chlorohydroquinone, o bromohydroquinone, 4phenyl catechol, 4-t-butyl catechol, pyrogallol,

4butyl pyrogallol, nordihydroquiauretic acid, 4,5-dibromocatechol, 3,5,6 tribromo 4 phenyl catechol, lphenyl-3-pyrazolidone, ascorbic acid, Phenidone B, and the like, and mixtures thereof.

The developer may be present in the pellicle in any suitable concentration, for example, between about 7.0 and about 28.0 percent by weight of the pellicle 10. The developer can be dispersed or dissolved in the pellicle 10 before its formation, but it could also be added during formation, or subsequently, e.g., by imbibing from a solution of developer. Thus, an aqueous solution of polyvinyl alcohol can be mixed with the developer and then spread as a thin lm on a suitable backing material such as baryta paper previously coated with a release agent such as cellulose acetate. After the water has evaporated from the coating, the resulting film can be stripped from the cellulose acetate layer on the paper backing and rolled onto a drum or reel or mounted on a card frame or the like. The pellicle 10 when so fabricated is, as is the developer contained therein, stable for many months in storage.

The web 12 comprises any suitable moist material which contains an activator for the developer. Thus, as shown in FIG. 1, the web 12 may comprise a moist gel layer 16 containing the activator and backed by a flexible support such as paper, paperboard, plastic, or the like. Such moist gel may be, for example, a set aqueous gel of agar, gelatin, sodium alginate, carrageenan, vegetable gums, mixtures thereof, or the like.

The activator comprises any suitable agent capable of activating the developer. For example, activator for the developers named above can be an organic or inorganic water soluble alkaline material such as ethanolamine, 1,3-propanediamine, diethanolamine, sodium hydroxide, potassium hydroxide, sodium carbonate, mixtures thereof, or the like.

The activator should be present in a concentration sufficient to activate enough developer to accomplish the desired latent image development. For example, a concentration of between about 0.5% and about of activator, by weight in the web coating formulation is usually sufficient depending on choice of activator and coating thickness. Other relative concentrations can also be used.

Referring again to FIG. 1, the pellicle 10 is shown disposed between the web 12 and photographic lm 14, the latter comprising an active layer containing the latent image-bearing material, e.g., silver halide in gelatin, disposed on a flexible transparent support 22, such as thin polyester film or the like.

The development of the latent image is carried out, in accordance with the present method, by simultaneously contacting the film 14 with the pellicle 10 While the web l 12 is also in contact with the pellicle 10 to form a laminated sandwich. Moist activator in the webs gel layer 16, contacts developer in the pellicle 10, dissolving and activating the latter, which in turn contacts and develops ythe latent image-forming agent, i.e., silver halide in the lm layer V20. Only a small amount of pressurev is needed, sufficient only to assure good, uniform contact.

When development is completed, the web 12 is removed carrying with it the pellicle 10 which preferentially adheres to the surface of the gel layer 16. If desired, the developed film 14 can then be passed into contact with a fixing agent such as sodium, ammonium or potassium thiosulfate, ammonium, sodium or potassium thiocyanate, or the like.

A second embodiment of the present invention, utilizing generally the same components previously described, is schematically illustrated in FIGS. 2A and 2B of the accompanying drawings. FIG. 2A shows a developer sheet 30 comprising a backing support 32, a developer-bearing layer 34 and a release layer 36 disposed between layer 34 and support 32. The release layer 36 may comprise cellun lose acetate or another material, such as ethyl cellulose, gum arabic, or the like, capable or readily permitting the stripping of layer 34 therefrom. The developer-bearing layer 34 generally corresponds to the pellicle 10 of FIG. l. An activator-containing web 12a, generally corresponding to the web 12 of FIG. 1, is also provided and contains layers 16a and 18a similar to the layers 16 and 18, respectively.

When FIG. 2B is compared with FIG. 2A, it is seen that in FIG. 2B, the developer-bearing layer 34 is on a surface of layer 16a of web 12a rather than on sheet 30, as in FIG. 2A. This transfer is accomplished, in accordance with the present method by pressing the developer sheet 30 and web 12a into contact with each other so that the developer-bearing layer adheres to the webs gel layer 16a, and then separating the sheets. This transfer is not carried out until the photographic medium (not shown) is to be developed. Preferably, as soon as the transfer is completed, the web 12a and the photographic medium are brought into contact so that the developer bearing layer 34 is placed in contact with the silver halide-bearing layer of the medium. Activator from the gel layer 16a dissolves and activates the developer in the developer-bearing layer 34 which in turn brings about development of the latent image in the photographic medium. After delamination, the web 12a (including layer 34) is discarded.

A further embodiment of the present invention is depicted schematically in FIG. 3 of the drawings. In this version, a developer sheet 40 is provided which is similar to the developer sheet 30 of FIG. 2a in that it contains a backing support 42 and a developer-containing layer 44 and an interposed layer 46 which, however, permanently bonds the developer-containing layer 44 to the backing support so that upon contact with a web it will not preferentially adhere thereto but will remain with the support 42 upon delamination. A web 12b containing a support layer 18b and an activator-bearing layer 16b, similar to the web 12, support layer 18 and layer 16, respectively, is also provided. The layer 46 can be any suitable bonding material such as hardened gelatin.

The system of FIG. 3 is utilized by bringing the developer sheet 40 into contact with the web 12b, with the developer-containing layer 44 abutting the gel layer 16b. Contact is sustained for a time suicient to permit the imbibing by, or transfer to the gel layer 16b of, developer in the developer-containing layer 44 in an amount suicient to adequately develop the latent image of exposed microtilm or the like to be subsequently contacted by the gel layer 16b. Usually, only a relatively short contact time between layers 44 and 16b is required, for example, about 5 seconds to about 30 seconds to effect the transfer. Transfer times Will depend on the nature and concentration of the materials utilized. After the transfer is completed, the developer sheet is discarded and the web 12b and the photographic medium to be developed contact each other, with the gel layer 16b disposed in contact with the silver halide-containing portion thereof, until desired image development is achieved, after which the web 12b is disposed of.

Each of the foregoing embodiments can be carried out in a diffusion transfer mode by including nucleating materials in the pellicle or developer-containing layer or in an adjacent layer, which layer is transferred to and remains with the activator web after delamination, and by including a suitable complexing agent in the activator web for the silver halide. Thus, nucleating materials, such as the following, can be incorporated: metallic sulfides, particularly those of the heavy metals such as lead, cadmium, zinc, nickel or silicon; metallic selenides such -as those of lead, nickel, zinc or antimony; and colloidal metals such as the precious metals, silver and gold being particularly suitable. Alternatively, a separate layer of, for example, polyvinyl alcohol, gelatin, water permeable cellulose esters such as hydroxyethylcellulose, hydroxypropylcellulose, or the like, or suitable combinations, can include nucleating materials and can be disposed on the activator web by separate transfer thereto before developing. These are usually dispersed in concentrations of about 0.001-0.1% by weight relative to the pellicle weight when located therein. Corresponding concentrations can be calculated for different locations in the system.

Examples of suitable silver halide complexing agents include: sodium thiosulfate, potassium thiosulfate, sodium sulfite, the lower aliphatic amines, and the like. These are usually dispersed in concentrations of about 3.5% to about 15.0% by weight relative to the total coating weight of the formulation. The foregoing, and other nucleating materials and complexing agents are well known to the art.

The diffusion transfer mode confers several advantages. In this regard, a positive print is produced. Moreover, virtually all of the unused silver halide can be removed from the photosensitive medium in a one-step procedure, thereby resulting in greater convenience and lbetter stabilization of the medium after processing.

The following Examples, in which all parts are by weight will further illustrate this invention.

Example 1 To 100 parts of a 3.0% by weight solution of 72-60 Elvanol (a polyvinyl alcohol sold by DuPont) are added 1 part of hydroquinone, 1.2 parts of ascorbic acid and 0.2 part of phenidone as developing agents. The mixture is coated on -a sheet of baryta paper which has been subbed with a coating of cellulose triacetate. After drying, the coating is stripped from the baryta paper to provide a pellicle of about 0.2 mil thick.

A gel web is prepared by adding 4.8 parts of diethanolamine as activator to 2.0 parts of agar as binder dissolved in 100 parts of water.

In processing a silver halide microfilm which has been exposed to form a latent image thereon, the pellicle is interposed between the emulsion layer of the microfilm strip and the agar material of the web. The combination is then pressed together to form a laminated sandwich and maintained together for about 60 seconds. Thereafter, the web is removed and the pellicle is carried with it to yield a developer image on the microfilm.

Example 2 Subbed baryta paper is coated as in Example 1 except that the developer-containing coating is not stripped from the paper. The coated paper is brought together with a rweb prepared as in Example l with the developer-containing coating in direct contact with the gel layer of the web. Thereafter the web is separated from the baryta paper, carrying with it the developer-containing layer. The web is then brought together with the microfilm strip for about 20 to 40 seconds lwith the developer-containing layer in direct Contact with the emulsion side of the microfilm to develop the microfilm. Thereafter the web is removed, carrying with it the developer-containing layer.

Example 3 Baryta paper is coated as in Example 1 but is subbed with a layer of hardened gelatin, about 0.1 mil thick. The coated sheet is brought together with a web prepared as in Example 1 using only slight pressure, about 1.25 p.s.i.g., for about 20 seconds. Thereafter the coated sheet is removed and the agar material of the web brought in oontact with the emulsion side of an exposed microfilm strip.

After contact of about 40 seconds, the gel web is removed yielding a developed image on the microfilm.

Example 4 A pellicle is prepared as in Example 1 except that 0.02 part of silver sulfide (AgzS) and 0.009 part of cadmium sulfide (CdS) as nucleating materials are added to the polyvinyl alcohol before coating. A web is prepared as in Example 1 except that 5.0 parts of sodium thiosulfate (Na2S2O35H2O) as silver halide complexing agent is added to the agar before coating. An exposed silver halide microfilm strip is processed by interposing the pellicle between the emulsion layer of the microfilm strip and the agar material of the web. The combination is pressed together to form a laminated sandwich and maintained together for about 60 seconds. Thereafter, the web is removed and carries the pellicle with it as well as unexposed silver halide grains from the microfilm emulsion to yield a developed, stable microfilm negative and a positive stable print on the web.

The method of the present invention thus involves contacting of a developer-bearing pellicle or sheet and an activator-bearing web either immediately before or during contacting of one of these with the photographic medium. During the latter contacting, developer and activator are in contact with each other and developer contacts the silver halide portion of the medium. Yet no contacting of the medium, sheet and web occurs except immediately prior to or at the time when developing is to be carried out. Thus, the integrity of the web (with activator) and pellicle or sheet (with developer) can be totally preserved for long periods of time before use. The moist web can be stored almost indefinitely with proper packaging, as can the pellicle or developer sheet and photographic medium.

During processing, the film, developer sheet and activator web can be easily fed into proper relative positions into and out of contact with one another, as described above, through the use of simple storage and transfer equipment. Moreover, such components and accessory equipment can be easily housed in camera bodies and in microfilm display and read out devices and the like. Accordingly, simple on-the-spot developing of photographic film and the like can be achieved without the expense, time and ditiiculties previously encountered in this art. Other advantages are as set forth in the foregoing.

Various modifications, changes, alterations and additions can be made in the present system, its components and in the present method, its steps and parameters. All such modifications, changes, alterations and additions as are within the scope of the appended claims form part of the present invention.

What is claimed is:

1. A method of photographic processing, comprising:

(a) interposng in spaced relation a sheet comprising an unsupported extent of thin film containing removable developer for a silver halide photographic latent image between an exposed silver halide photographic lm emulsion, bearing a latent image, and a separate moist activator web containing removable activator for said developer;

(b) simultaneously contacting :said thin film with said web and with said film emulsion whereby to transfer said activator and said developer to said emulsion; and

(c) removing said film emulsion from said contact after development of said latent image.

2. The method of Claim 1 wherein said web is formed of moist gel and said thin film is dry.

3. The method of Claim 1 wherein said film comprises polyvinyl alcohol with said developer dispersed therein.

4. The method of Claim 1 wherein said film includes nucleating materials and said web includes silver halide complexing agent.

5. The method of Claim 1 wherein said web comprises an agar film with said activator dispersed therein. ,y 6. The method of Claim 1 wherein said thin film carries nucleating materials for transfer to said web and wherein said web includes silver halide complexing agent. 7. A system for photographic processing, said system comprising:

(a) a moist activator web containing removable activator for said developer; (b) a sheet comprising an unsupported extent of thin developer iilm containing removable developer for a silver halide photographic latent image; (c) an exposed silver halide emulsion;

said moist activator web, thin developer film, and exposed silver halide emulsion being aranged in the above order; and (d) means for simultaneously contacting said thin developer film with said activator web and said silver halide film emulsion, for transference of said activator and developer to said emulsion. 8. The system of Claim 7 wherein said web is formed of moist gel and said thin film is dry.

9. The system of Claim 7 wherein said film comprises polyvinyl alcohol with said developer dispersed therein. 10. The system of Claim 7 wherein said film includes nucleating materials.

11. The system of Claim 7 wherein said web comprises an agar film` with said activator dispersed therein.

UNITED STATES PATENTS 3,179,517 4/1965 Tregillus et al. 96-5() 3,260,598 7/ 1966 Yutzy et al. 96-95 3,413,181 11/1968 Goldhammer 96--50 3,425,832 2/1969 Bornemisza 96-63 3,576,632 4/1971 Bornemisza 96-76 R 3,615,482 10/1971 Cronig 96-63 3,623,868 11/ 1971 Cronig 96-63 3,680,462 8/1972 Cronig 96-50 3,682,638 8/1972 Kosti 96-95 MARY F. KELLEY, Primary Examiner U.S. Cl. X.R. 96-63, 76 R 

